Improvement in pneumatic pumps for refrigerating apparatus



D. L. HOLDEN.

PNEUMATIC PUMP For; REFRIGERATING APPARATUS, Ac.

No.188,137. Pacenned March 6,1371.

WITNESSES N. PETERS, PHDYO-LITHOGRAFHER. WASHING'TDN, D C.

AUNITnn STATE@ PATENT OFFICE.

DANIEL L. HOLDEN, OF COVINGTON, KENTUCKY.

IMPROVEMENT IN PNEUMATIC PUMPS FOR REFRIGERATING APPARATUS, duc.

Specification forming part of Letters Patent No. 188,137, dated March 6,1877 application led January 31, 1877.

To all whom it may concern:

Be it known that I, DANIEL L. HOLDEN, of Covington, in/the county ofKenton and State of Kentucky, have invented a new and Improved PneumaticPump for Refrigerating Apparatus and other Purposes; and I do herebydeclare that the following is a full, clear, and exactdescription of thesame, reference being had to the accompanying drawing, forming part ofthis specification, in which- Figure l is a vertical longitudinalsection, with the elevated position of piston when lifting the valveshown in dotted lilies. Fig. 2 is a detail inside view of the topcylinder-head.

My invention relates to certain improvements in pneumatic pumps,designed more particularly for facilitating the evaporation of volatileliquids in making ice, but applicable to all uses for which such pumpsmay be employed.

The object of my invention is to make, as far as practicable, a perfectvacuum-pump, or a pump in which there is practically no residuum orcushion of the elastic iiuid left in the chamber of the cylinder at theend of the stroke, and yet at the same time preserve a strong anddurable construction for the pump.

My pump belongs to that class of pneumatic pumps in which a valve ofgreater diameter than the bore of the cylinder is used to form thecylinder-head, or in which thecylinderhead is made yielding, so as topermit the plain face of the piston to strike against said valve oryielding cylinder-head, to thoroughly expel all air or gas, while itsyielding character prevents the shock that would otherwise'be prov ducedby the' piston.

My improvement consists in combining an imperforate piston with a valveof the above construction, and a cylinder having but a singleinlet-valve,.in such a manner that the piston, in forcing out the chargeof air or gas, produces a partial vacuum beneath the same, and passesthe inlet orifice, whereby th/e compressed gaseous charge held in saidinletvalve chamber is allowed to pass beneath the piston, and to expandinto and be absorbed by the partial vacuum, so that upon the downwardexhaust-stroke of the piston there will be no charge of compressed airor gas in the inlet-valve chamber to expand above the piston, andprevent, by its elasticity, the perfect exhausting-stroke of saidpiston. An outlet check-valve is employed in the opposite end of thecylinder from the inlet for the discharge of the compressed charges ofthe air or gas taken from-the said inlet-valve chamber.

In the drawing, A represents a portion of any frame-work, upon which thepump may be mounted. Bis the pump-cylinder, which preferably occupies avertical position; and C is a solid imperforate piston, connected withand operated by a piston-rod, D, which emerges from the bottom end ofthe cylinder. E is the top cylinder-head, which is made with an enlargedcavity to receive the valve, and is bolted to the ilange a of the bodyof the cylinder. The cavity or chamber in the cylinder-head is made of agreater diameter than the bore of the cylinder, so as to receive thevalve F, which is also of a larger diameter than said bore. This valveis constructed of a cup shape, with a dat ground bottom, and seatsitself upon the inner edges of the end of the cylinder, being guided inits movements in the cylinder-head by projections h, cast upon the sidesof said head. G is the inlet for the air or gas, provided with aninwardlyopening check-valve, c,- and H is the outlet for the said air orgas, opening into the cylinder-head through an orifice; d, beside thecup- ,.valve.

As the piston descends the check-valve c opens, and air or gas is drawnthrough the inlet Gto fill the space above the piston, and as the pistonrises the check-valve is closed, and the air or gas lifts the largecup-valve, and is forced through orilice d to the outlet H, while at thesame time a partial vacuum is produced beneath the piston. Asgthe pistoncontinues to rise its smoothly-grond face strikes the smoothly-groundbottom of the cup-valve, and producesa direct contact between the bottomof the valve, which forms the end of the vacnum-chamber, and the movablepiston, with no traces of an air-cushion between the same. Consequently,when the piston commences to descend, the vacuum-chamber commences toenlarge from zero, and the most perfect mechanical exhaustion attainableis secured,

which renders the pump specially adapted to inducing evaporation 1nicemaking, and other uses requiring a perfect vacuum action.

It will be seen that. so far as described, this pump is single-acting,and this is substantially the case in its operation; but it is to alimited extent double-acting, which peculiarity is designed only torender it a more perfect vacuum-pump. As the piston rises it will beseen that there is a degree of compression in the upper part of thecylinder, and as the piston passes over thc inlet-orifice a portion ofsuch compressed air or gas would be caught in the space between theinner orifice of the inlet and the check valve; and if, upon the descentof thc piston, this were allowed to expand above the piston, it wouldseriously interfere with the perfect exhausting,` action of the pump. Toremedy' this defect I have arranged the piston, in lifting' thecupvalve, to pass the inlet-orih`ce, as shown in dotted lines,whiclipermits the retained charge ol' compressed fas to expand and difi'nseitself beneath the piston, beingabsorbed by the partial vacuum producedbeneath the same. Then, upon the descent of the piston, the air or gasis driven out through a checkvalve,f, in the bottom, and is conductedthrough a port, g, arranged longitudinally beside the cylinder, to theoutlet-pipe H.

To prevent leakage of air through the stui ing-box about the piston-rod,said stuffing is hermetically sealed by a water-seal, formed by acup-shaped box, I, which surrounds said stuffing-box, and lits in agroove, l, formed in the lower cylinder-head, which box I is alsoprovided with a stuffing-box, k, to hold the Water in.

From the above description it will be seen that this pump is as nearly aperfect vacuumpump as it is possible to obtain by mechanical means, andits simplicity, freedom from derangement, and perfect action recommendit for many uses too varied to enumerate.

Having thus described my invention, what I claim as new is- Thecombination, with the cylinder B, having an inlet check-valve, G, and auescapevent below the piston, of' the movable valve F, made of greaterdiameter than the bore of the cylinder, and the imperforate piston C,arranged to pass the inlet-orifice in forcing out the contents of' thecylinder, substantially as and for the purpose Set forth.

The above specification of my invention signed by me this 24th day ofJanuary, 1877.

D. L. HOLDEN. Witnesses:

EDWD. W. BYRN, CHAs. A. PETTIT.

HAM*

